mm: cma: simplify cma_maxchunk_get()

The function opencodes for_each_clear_bitrange(). Fix that and drop most
of housekeeping code.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Yury Norov (NVIDIA) <[e-mail]>
Acked-by: David Hildenbrand <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

mm/cma_debug.c

···
 	for (r = 0; r < cma->nranges; r++) {
 		cmr = &cma->ranges[r];
 		bitmap_maxno = cma_bitmap_maxno(cma, cmr);
-		end = 0;
-		for (;;) {
-			start = find_next_zero_bit(cmr->bitmap,
-						   bitmap_maxno, end);
-			if (start >= bitmap_maxno)
-				break;
-			end = find_next_bit(cmr->bitmap, bitmap_maxno,
-					    start);
+		for_each_clear_bitrange(start, end, cmr->bitmap, bitmap_maxno)
 			maxchunk = max(end - start, maxchunk);
-		}
 	}
 	spin_unlock_irq(&cma->lock);
 	*val = (u64)maxchunk << cma->order_per_bit;